1. Technical Field
The present disclosure relates to a solder paste mounting tool, more particular to a solder paste mounting tool applied to a ball grid array (BGA) process.
2. Description of Related Art
In recent years, functions and efficiency of technically advanced consumer electronic products have been improved, so that chips used in the electronic products need to have some advantages such as fast computing speed and small volume.
A quad flat package (QFP) is one of the chip package techniques in early days, metal conductive wires surrounded a chip are used as connecting pins. However, the area of the chip may limit the number of the connecting pins of the chip, and such a chip has poor electrical characteristics and thermal conductivity. For the past few years, another so-called ball grid array (BGA) chip is increasing demanded. The BGA chip includes connecting pads in an array arrangement, and solder paste formed on the connecting pads replace the connecting pins utilizing the metal conductive wires. Compared with the quad flat package, one advantage of the ball grid array chip is that when the BGA chip and the QFP chip have the same area, the number of the connecting pads of the BGA chip is greater than the number of the connecting pins of the QFP chip, such that the area and weight of the BGA chip can be half as much as those of the QFP chip.
A conventional solder paste mounting tool applied to a BGA process includes a steel plate having a hollow region, a screen plate, and a cover. First, a chip is placed on the steel plate, and connecting pads of the chip are aligned with the hollow region of the steel plate. Then, the cover is assembled with the screen plate, such that the chip is sandwiched between the cover and the screen plate and the connecting pads face the screen plate. Then, the screen plate is applied with solder paste. After the solder paste penetrates the screen plate and adheres to the connecting pads, the cover may be detached.
However, when detaching the chip, a user needs to tap the screen plate with his fingers, such that the connecting pads of the chip can be separated from the screen plate. As a result, not only the fingers need to be cleaned because of touching the solder paste, but also the connecting pads having the solder paste are difficult to be separated from the screen plate in a perpendicular direction, such that the thickness of the solder paste is difficult to be uniform. Moreover, different users may have different operation errors, such that the quality of the balls formed from the solder paste are difficult to be controlled. In addition, each of the chips adhered with the solder paste needs to be placed on a mold plate to perform subsequent processes (such as laser alignment), thus wasting time.